Pavement.



No.. 727,505. PATBNTED MAY 5, 190s. P. J. WARREN.

` PAVEMENT.

APPLIOATION FILED MAY 15, 1901.

Patented may s, 1903.`

PATENT OFFICE.

FREDERICK .IOHN WARREN, OF NEWTON, MASSACHUSETTS.

PAVEMENT'.

`SPIECLEXIGATION forming part of Letters Patent No. 727,505, dated. May5, 19.03.

Y Application filed May 16, 1901. Serial No. 60,450; (No specimens.)

base of mineral matter and a plastic unitingl medium consisting of anatural or artificial asphalt- .or coal-tar composition, which areintimately associated together and used as the main upper or topsurfacing of the road-bed.\

The invention is based upon my discovery that to insure the bestconditions of constru ction, wear, and life in such Ipavements theportion of the pavement to which 'my invention relates must be made asdense, as free from voids as possible, and also stable and non-liable todisplacement, and uponl my further discovery that what has ordinarily.been supposed to be the best provision for eliminating voids andestablishing stability has, as a matter of fact, been almost .thepoorest provision .for accomplishing these purposes.' The provisionusually accepted as the best is that in'which the mineral matterused asa basis of the pavementand united by the plastic asphalt vehicleshallvbe in the. shape of a sand or line gravel. ror, as I have,discovered by experiment that there is a smaller percentage of voids ina pavement which contains, mineral components which are of relati'velylargesize. v, The method has been in the construction of this class ofpavements to exclude from its cornposition all pieces of stone or sandlarger than one-tenth of an inch in diameter; but

` by so doing the smallest percentage of voids that it has been possibleto produce has been twenty-one per cent. ot thetaggregate, while by theuse of the'larger-sized grains or piecessay up to those whichwill passthrough a two inch ring--and employing with` theselarger grains properquantities ot the smaller sizes down to an impalpable powder it ispossible to reduce the voids of the mineral base below ten per cent. ofits bulk, and lsuch a This, however, is an ermixture when assembled andcompacted to-l gether will form a dense, solid, homogeneous, compactbody with the smallest percentage of voids and possessing the highestdegree of stability, and one in which the largest and smallest piecesare associated with each other in'- discriminately throughout thestructure, and one which, Ibecause of the sizes of the pieces and theirarrangement with respect to each other, offers the smallest areas ofsurfaces for v the attachment of the plastic composition to them, sothat not only -is a superior binding effect or union obtained`by theplastic composition buta smaller quantity of it is necessary for thepurpose of obtaining the superior result or product. I prefer to usefrom one to three per cent. of impalpable powder, from tento thirty percent. of material between impalpable powder and one-fourth 'of "an inchin size, and from fifty to eightytperv cent. 4of material .larger thanone-fourth of t an inch in size. I have found that these'ingredientswhen associated together produce a mass or body having less than twentyper cent. of voids. I prefer to use as the uniting or plasticcomposition one which comprises asphalt and au voil-flux heated to amoderate i heat to provide the requisite fluid-ity; butI do not confinemyself to any special form of artificial or ynatural asphalt.- It will-be uny derstood that the mineral components are not arranged lin theform of layers of. the same size, but are mingled with each other fromtheeupper to the lower surface of Ythe pavement, and that the placticcomposition permeates the'entire mass, uniting-the variousszedparticles.thereof, filling the voids, and forming the surfaces.

used as the upper or wearing section of arcadbed and that it 'may becovered, if desired, with a relatively thin surfacing of clearasphalt-ceme'nt or an asphalt or bituminous composition of any desirednature. In some instances there may be rolled into this Vthin surfacingwhile it is yet soft suicient sand, gravel, or-ine stone to` prevent itsdisplacement by trailc. y

Iwill Inow describe .the invention in coul nection with the drawings,wherein'- l' Figure J1 is a view in horizontal section: of

enough of a pavement to illustrate in a con- It will be understoodthatthispavement is.

- ventional way the features of my invention,

while Fig`s. 2 and.3 are corresponding views .representing the additionofva surfacing to the structure of Fig. 1.

In the drawings, A represents the portion of theA road-bed to which myinvention relates and which may be called the wearingsection of the-road-bed and is the portion which covers and is supported by themacadam or other foundation B. In the wearingseetion are representedsome of the'larger'mineral pieces, some pieces of intermediate size, andsome of the smaller pieces and also the plastic composition Awhichunites themtogether, and C represents the surfacing to which I havereferred. somewhat thicker in Fig. 3 than in"Fig. 2. It will beunderstood, however, that the drawings are simply illustrative and thatit is not possibletorepresent the variations in the sizes-of the mineralpieces, atoms, and powder which are employedin producing my improvedresult.

In laying the wearing-surface the pieces, particles,r and atoms 4of thehase areintimately associated with the plastic asphalt composition,which is thenspread uniformly upon the prepared foundation and whichviusetting becomes very dense, solid, stable, and freer' from voids thanany pavement of which I have knowledge. This density of the structure,stability, and its -relative freedom from voids Veryymuch improve thewearing properties of the pavement, its resistance to the action ofwater, and on account of its dense` structure prevents thevolatilization or oxidation of the essential oils in the cementingmedium, increases its life, and'while producing these improvements italsoenables the wearing-surface to be produced at a smallerV costbecause a smaller quantity of plastic asphalt materialis required thanwhere the percentage of voids is larger.

A pavement or wea-ringsection of a pave-` ment having the features ofthis Ainvention possesses 'various advantages, among which vare thefollowing: First, the percentage of mineral employed is-increased andthe per-' centage of plastic uniting-medium decreased as compared withanalogous pavements as` now laid; second, thewearing properties of thepavement are increased and improved, and this is due tothe employment ofa larger proportion of mineral to the proportion of the uniting mediumand also to the fact that the Y mineral base is of such a structure,owin g to the employment of a considerable percentage of relativelylarger pieces, larger than are now used, that a very rigid and stableeffect is obt-ained yandoue which reduces 4strain and wear upon theuniting medium, more of the wearV being borne by the mineral baseandless by the uniting medium than is common; third,

the interstices or 'voidsformed by such mineral components are also of adifferent character, in that they are larger and fewer, and thereforethe asphalt or bituminous uniting It is represented as -l ireasonsmedium contained in them forms a cellular structure, which is strongerand adheres better to the surfaces of the mineral components numerousand of less size.

application, however,Ido not claim, broadly, a binder yor cement of thischaracter. Ihave reserved the same to be claimed inmy cof pendingapplication Serial No. 60,819.

Having thus fully described my invention, I

of the United Statesl. A street-pavement mixture composed of threeinches down to an impalpable powder, from fifty to eighty per cent. offsuch mineral ingredients lying between one-fourth inch and three inchesindiameter, in combination with a bituminous binder.

y2. A street-pavement mixture composed of mineral ingredients of severalgrades from an impalpable .powder to three inches in diameter, overfifty per cent. of such ingredients being larger than one-,fourth inchin diameter, and a bituminous binder.

3. A street-pavement mixture composed of tween one-fourth inch tothreeinches in diameter, approximately ten to forty-nine per cent. between animpalpable powder and onefourth inch in diameter, and approximately oneto three per cent. of an impalpable powder, in combination with abinder.

mineral or wearing ingredients, of which apfproximately fifty to eightyper cent. lies betweenone-fourth inch and three inches in di-A fourthinch in diameter, and approximately one tothree in combination with abituminous binder, of Iwhich the soft, oily constituent is sufficientlygreat to render the binder itself too flexible to maintain the structurerigid.

5.- In a street-pavement, a bituminous min-` eralstructure, the mineralingredients of whichfare mixed and of several grades, so graded as togive the structure an inherent stability. f

i5.' A bituminous street-pavementstructure containing mixed mineralingredients of such grades as to give the structure an inherentstability.

7. A bituminous street-pavement mixture comprising a binder incombination with a y Because of the inherent Stability obtained' lattermaybe as soft as desirable. In this!" claim and desire to secu reA byLetters Patentv mineral ingredients ranging in grades from 4. Astreet-pavement mixture composed of per cent. an impalpable powder,

than where the voids or interstices are more IOO mineral or wearingingredients, of which approximately fifty to eighty per cent. are be-IIO ameter, approximately ten to forty-nine per cent. between animpalpable powder and one- K mineral structureol inherent stabilitycomposed of iwearing material of several grades uniformly mixed.

8. A street-paving mixture comprising a bituminous binder in combinationwith aY mineral structure 'of inherent stability.

9. A street-pavement Wearing-section composed of a. mineral structure ofinherent stability formed of several grades of material so proportionedas to have a per cent. of voids less than twenty-oneper cent. of thewhole, in combination with a comparatively soft bituminous binderfilling said voids and rendering the Whole permanent `in nature andelastic and waterproof in character.

10. A mixture for street-paving purposes Vcomposed of a bituminousbinder and a. mixture of mineral ingredients of several gradeshaviugless than twenty-one percent. of voids, the binder being sufcientin quantity to fill the voids.

l1. A street-paving structure composed of a mixture of mineral orwearing ingredients, and a plastic binder, the space between the one percent. of the whole, and the-plastic l binder occupying said space. v

12. A mixture of mineral or wearing ingredients of several grades, theingredients of the descending grades in size and quantity being soproportioned to each other and to the voids existing' in the largergrades as to fill the voids and impart t'o the structure an inherentstability, in combination Iwith a bi tuininous cement or binder.

13. A mixture to be used as a pavement having an inherent stabilitycomposed of mineral or wearing ingredients o f several grades,

the grades being thoroughly mixed and thereby uniformly distributedthroughout the mass and being of sizes and quantities so propor-v tionedthat ingredients of the same grade are uniformly in contact with eachother, and a bituminous cement or binder.

FREDERICK JOHN. WARREN. Witnesses: i

F. F. RAYMOND, 2d, J. M. DoLAN.

